CEFACLOR- cefaclor capsule
A-S Medication Solutions


Rev. 09/15

Rx Only

To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefaclor and other antibacterial drugs, cefaclor should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.


Cefaclor Capsules, USP are a semisynthetic cephalosporin antibiotic for oral administration. It is chemically designated as 3-chloro-7-D-(2-phenylglycinamido)-3-cephem-4-carboxylic acid monohydrate. The molecular formula for cefaclor is C15 H14 ClN3 O4 S•H2 O and the molecular weight is 385.82.

Each capsule contains cefaclor monohydrate equivalent to 250 mg (0.68 mmol) or 500 mg (1.36 mmol) anhydrous cefaclor. The capsules also contain black iron oxide, croscarmellose sodium, FD & C Red No.3, FD & C Blue No.2, gelatin, magnesium stearate, corn starch, and titanium dioxide.

The color of the capsule powder is white to off white.


Cefaclor is well absorbed after oral administration to fasting subjects. Total absorption is the same whether the drug is given with or without food; however, when it is taken with food, the peak concentration achieved is 50% to 75% of that observed when the drug is administered to fasting subjects and generally appears from three fourths to 1 hour later. Following administration of 250-mg, 500-mg, and 1-g doses to fasting subjects, average peak serum levels of approximately 7, 13, and 23 mcg/mL respectively were obtained within 30 to 60 minutes. Approximately 60% to 85% of the drug is excreted unchanged in the urine within 8 hours, the greater portion being excreted within the first 2 hours. During this 8-hour period, peak urine concentrations following the 250-mg, 500-mg, and 1-g doses were approximately 600, 900, and 1,900 mcg/mL, respectively. The serum half-life in normal subjects is 0.6 to 0.9 hour. In patients with reduced renal function, the serum half-life of cefaclor is slightly prolonged. In those with complete absence of renal function, the plasma half-life of the intact molecule is 2.3 to 2.8 hours. Excretion pathways in patients with markedly impaired renal function have not been determined. Hemodialysis shortens the half-life by 25% to 30%.


Mechanism of Action

As with other cephalosporins, the bactericidal action of cefaclor results from inhibition of cell-wall synthesis.

Mechanism of Resistance

Resistance to cefaclor is primarily through hydrolysis of beta-lactamases, alteration of penicillin binding proteins (PBPs) and decreased permeability. Pseudomonas spp.,Acinetobacter calcoaceticus and most strains of Enterococi (Enterococcus faecalis , group D streptococci), Enterobacter spp., indole-positive Proteus, Morganella morganii (formerly Proteus morganii), Providencia rettgeri (formerly Proteus rettgeri) and Serratia spp. are resistant to cefaclor. Cefaclor is inactive against methicillin-resistant staphylococci, β lactamase-negative, ampicillin-resistant strains of H. influenzae should be considered resistant to cefaclor despite apparent in vitro susceptibility to this agent.

Antibacterial Activity

Cefaclor has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.

Gram-positive Bacteria

Staphylococcus aureus ( methicillin -susceptible only)

Coagulase negative staphylococci ( methicillin -susceptible only)

Streptococcus pneumoniae

Streptococcus pyogenes (group A β-hemolytic streptococci)

Gram-negative Bacteria
Escherichia coli
Haemophilus influenzae (excluding β-lactamase-negative, ampicillin-resistant strains)
Klebsiella spp.
Proteus mirabilis

The following in vitro data are available, but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentrations (MICs) less than or equal to the susceptible breakpoint of cefaclor. However, the safety and effectiveness of cefaclor in treating clinical infections due to these bacteria has not been established in adequate and well-controlled trials

Gram-negative Bacteria
Citrobacter diversus
Moraxella catarrhalis
Neisseria gonorrhoeae

Anaerobic Bacteria
Bacteroides spp.
Peptococcus spp.
Peptostreptococcus spp
Propionibacterium acnes Susceptibility Test Methods

When available, the clinical microbiology laboratory should provide the result of in vitro susceptibility test results for antimicrobial drugs used in resident hospitals to the physician as periodic reports that describe the susceptibility profile of nosocomial and community-acquired pathogens. These reports should aid the physician in selecting an antibacterial drug for treatment.

Dilution Techniques

Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized method (broth, agar, or microdilution)1,3. The MIC values should be interpreted according to criteria provided in Table 1.

Diffusion Techniques

Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. The zone size provides an estimate of the susceptibility of bacteria to antimicrobial compounds. The zone size should be determined using standardized test method2,3. This procedure uses paper disks impregnated with 30-mcg cefaclor to test the susceptibility of microorganisms to cefaclor. The disc diffusion interpretive criteria are provided in Table 1.

Table 1: Susceptibility Test Interpretive Criteria for Cefaclor
Microorganisms 1,2 Minimal Inhibitory Concentration (mcg/ mL ) Zone Diameter (mm)
Streptococcus pneumoniae ≤1 2 ≥4

1 Susceptibility of staphylococci to cefaclor may be deduced from testing only penicillin and either cefoxitin or oxacillin

2 Susceptibility of Streptococcus pyogenes to cefaclor may also be deduced from testing penicillin

A report of susceptibile indicates that antimicrobial is likely to inhibit growth of the pathogen if the antimicrobial compound reaches the concentrations at the site of infection necessary to inhibit growth of the pathogen. A report of Intermediate indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where a high dosage of drug can be used. This category also provides a buffer zone that prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of Resistant indicates that the antimicrobial is not likely to inhibit growth of the pathogen if the antimicrobial compound reaches the concentrations usually achievable at the infection site; other therapy should be selected.

Quality Control

Standardized susceptibility test procedures require the use of laboratory controls to monitor and ensure the accuracy and precision of supplies and reagents used in the assay, and the techniques of the individuals performing the test, 1,2,3 Standard cefaclor powder should provide the following range of MIC values noted in Table 2. For the diffusion technique using the 30 mcg disk the criteria in Table 2 should be achieved.

Table 2: Acceptable Quality control Ranges for Cefaclor
QC Strain Minimal Inhibitory Concentration (mcg/ mL ) Zone Diameter (mm)
Escherichia coli ATCC 25922 1-4 23-27
Haemophilus influenzae ATCC 49766 1-4 25-31
Staphylococcus aureus ATCC 25923 27-31
Staphylococcus aureus ATCC 29213 1-4
Streptococcus pneumoniae ATCC 49619 1-4 24-32
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